The goal of this program is to advance the understanding of underlying pathology in sudden infant death, with particular reference to sleep pathology. During the 01 year we have conduceted sleep and wakefulness recordings on 15 premature infants, 16 hour recordings on eight full-term infants, several recordings (including 36-hour and all-night monitoring) on four sleep apneic children, and several recordings on members of families who have had at least one SIDS case. Our major findings are of marked upper airway apnea and central apnea in premature infants and term infants who have had a "near-miss". Data suggest that supper airway apneas are more dangerous to young children because of attendant hemodynamic consequences. Data are consistent with the hypothesis that sleep apnea can subclinically exist in SIDS victims and that it is brought to a fatal degree by some intervening variable such as an upper respiratory infection. We have demonstrated that upper airway apnea in children and adults is responsible for various arrhythmias which are only seen during sleep and are related to upper airway apnea. We propose to study the existence of such sleep arrhythmias in infants who present sleep apneic episodes.